Notes, summaries, assignments, exams, and problems for Geology

Sources of Earth's Internal Heat

The Earth's internal heat, the engine driving many geological processes, originates from several key sources:

• Primordial Heat: This is the leftover heat from the planet's initial formation and accretion.
• Core Formation: Significant heat was released as heavy elements, primarily iron and nickel, sank to form the Earth's core.
• Radioactive Decay: The continuous decay of radioactive isotopes within the crust and mantle, such as uranium-238, thorium-232, and potassium-40, is a major source of heat.
• Latent Heat: Heat is released from the crystallization and solidification of the liquid outer core to form the solid inner core.
• Tidal Heating: Frictional heat is generated by the gravitational forces exerted by the Moon and

Causes of Soil Pollution

• Industrial Activities

  • Chemical Spills and Discharges: Factories and manufacturing plants often handle chemicals that, if spilled or improperly disposed of, can seep into the soil.
  • Mining Operations: Mining activities expose and disperse heavy metals and other pollutants, which can contaminate surrounding soils.
  • Industrial Waste: By-products of industrial processes, such as slag and sludge, are often disposed of in landfills or directly onto land, leading to soil contamination.

• Agricultural Practices

  • Pesticides and Herbicides: These chemicals are used to control pests and weeds but often contain harmful substances that can persist in the soil and disrupt ecosystems.
  • Fertilizers: Excessive use of nitrogen and phosphorus-based

Tunnel Lining Fundamentals

Purpose of Tunnel Lining

• Support tunnel structure.
• Prevent water ingress.
• Improve durability.

Types of Tunnel Lining

• Concrete
• Shotcrete
• Steel
• Masonry

Sections of Tunnel Lining

• Crown: Top of the tunnel.
• Inverts: Bottom of the tunnel.
• Walls: Sides of the tunnel.

Types of Foundation Footings

• Spread Footing (Pad footing) – Supports a single column.
• Strip Footing (Continuous footing) – Continuous foundation beneath a wall.
• Raft Foundation – Covers the entire building footprint; distributes load on weak soils.

Understanding Foundation Settlement

• Definition: Downward movement due to soil compression.
• Notes:
  • Coarse soils: Settlement often ≤ 25 mm (rarely > 50 mm).
  • Loose sands below water table: More settlement.
  • Clay: Consolidation settlement,

1. What are the innermost layers of Earth?

The inner core is the innermost physical layer of the Earth. The core is the innermost chemical layer.

2. What evidence indicates that the outer core is liquid?

Evidence from earthquake waves indicates that the outer core is liquid.

3. How does Earth generate a magnetic field?

It surrounds Earth.

4. Compare the lithosphere and the asthenosphere

The lithosphere is a rigid layer. The asthenosphere is a plastic layer.

5. How is the crust different from the mantle?

The mantle has more iron. The crust is less dense than the mantle.

6. What are the four layers of the mantle?

• Lithosphere
• Asthenosphere
• Uppermost mantle
• Lower mantle

7. Which layer of the mantle has the greatest pressure? Explain

The lower mantle because pressure... Continue reading "Earth's Layers and Systems: Composition and Properties" »

Earth's Fundamental Motions

Two Primary Earth Movements

• Rotation: The spinning of Earth on its axis. Consequences: Day and night cycle, Coriolis effect.
• Revolution: The orbiting of Earth around the Sun. Consequences: Seasons, varying daylight hours.

Earth's Interconnected Spheres

The Four Spheres of Earth

• Atmosphere: The layer of gases surrounding Earth. It provides air for breathing and protects from harmful solar radiation.
• Hydrosphere: All water on Earth, including oceans, rivers, lakes, and glaciers. It plays a key role in the water cycle and supports aquatic life.
• Lithosphere: The rigid outer layer of Earth, consisting of the crust and upper mantle. It forms landmasses and ocean floors.
• Biosphere: All living organisms and their interactions with

What Are Rocks?

Rocks are solid aggregates of minerals. They are more common than individual minerals.

The Three Types of Rocks

There are three different types of rocks:

• Igneous
• Sedimentary
• Metamorphic

Igneous Rocks

Igneous rocks are formed from magma that has cooled and solidified.

Plutonic Rocks

These rocks are formed deep underground, and the cooling process is very slow. The slower the cooling process, the larger the crystals formed (e.g., granite).

Volcanic Rocks

These rocks are formed on the surface, often related to volcanoes. The cooling process is very quick, preventing the formation of visible crystals (e.g., obsidian, pumice).

Sedimentary Rocks

Sedimentary rocks are made of fragments of other rocks (sediments). They often contain fossils.

Formation

Unique Properties of Water

Water is a molecule that consists of two hydrogen atoms and one oxygen atom. Water is special because its highest density is in liquid form rather than solid form, which is the case for most substances. It is also called the “universal solvent” because of its ability to dissolve more substances than any other liquid found on Earth, due to its unique chemical composition and physical attributes.

Cohesion and adhesion are two very important water properties.

• Cohesion is the property that allows water molecules to stick to one another (e.g., a drop of water holding its shape).
• Adhesion is the property that allows water molecules to stick to another substance instead of slipping off.
• Capillary action is the movement of

1. Earth's Position in Space

   • Earth orbits the Sun at 67,000 mph, maintaining a delicate balance between gravity and velocity.
   • Life exists due to Earth's stable distance from the Sun, allowing liquid water and habitable temperatures.

2. Earth as an Energy and Matter System

   • All changes on Earth result from energy: inputs, storage, transformation, or outputs.

   • Two Primary Energy Sources:

     • Solar Energy: Drives photosynthesis, weather, and food webs.
     • Internal Earth Energy: Causes tectonic activity, earthquakes, and volcanic eruptions.

3. Solar Energy Pathways

   • Photosynthesis: Converts sunlight into chemically bonded energy (food, fossil fuels).
   • Heat Energy: Drives weather systems (e.g., hurricanes, tornadoes).

4. Energy Flow

   • Energy flows into, through, and out of Earth's